In the last few hours of your busy Pod A shift, you sign up for a patient with the chief complaint “penile pain.” His chart indicates a history of sickle cell and multiple prior urology appointments and ED presentations for recurrent priapism. As you enter the room, the patient yells, “Doc, help me!”
Priapism (named after the Greek god Priapus, god of fertility and protector of livestock) refers to an erection lasting longer than 4 hours in the absence of sexual stimulation or desire. The condition can be painful or painless, depending on the cause. Priapism affects about 0.73 per 100,000 men per year (1), and has a bimodal distribution (children and adults 20-50 years old).
CAUSES
In children, the most common cause of priapism is sickle cell disease. In children with a first episode of priapism and no known history of sickle cell, it is reasonable to send a hemoglobin, reticulocyte count, and hemoglobin electrophoresis.
For adults, priapism is most commonly caused by medications, such as trazodone. Other commonly implicated medications and drugs include antidepressants, phosphodiesterase inhibitors, methylphenidate, and cocaine. Other more rare causes of priapism include thalassemia, leukemia and other hematologic diseases, dialysis (potentially from heparin used during the procedure), total parenteral nutrition, amyloidosis, malaria, and certain spider envenomations. Non-ischemic priapism is often traumatic and can result from a spinal injury.
PATHOPHYSIOLOGY
As mentioned above, one of the most important distinctions in the diagnosis and management of priapism is between ischemic and non-ischemic priapism. Ischemic priapism is generally very painful with no reported history of trauma. This contrasts with non-ischemic priapism, which often results from spinal injury, and as a result, is usually painless.
If left untreated, ischemic priapism can cause fibrosis and permanent sexual dysfunction. Ischemic priapism is analogous to compartment syndrome: as venous plexuses are compressed, blood is essentially trapped in the penile sinusoids and gradually becomes more hypoxic and acidemic, leading to permanent tissue damage.
Even beyond the history and physical exam, ischemic and non-ischemic priapism can be differentiated based on a blood gas aspirated from the corpus cavernosum. Again, ischemic priapism will show more acidemic and hypoxic blood, which will often be darker and thicker.
Table from Reichman’s Emergency Medicine Procedures
DRAINAGE
The most important treatment for priapism is drainage. Before you attempt drainage, it’s important to review anatomy and make sure you have all the necessary equipment.
Image from Ting, HYZ: Cross-sectional anatomy of the penis
In the cross-section of the penis above, you can see the two corpora cavernosa above the corpus spongiosum, which contains the urethra. Both corpora cavernosa communicate through an incomplete septum. The dorsal veins and arteries run in the 12 o’clock position along the dorsum of the penis. Adjacent to the dorsal veins and arteries are the dorsal nerves, which are important landmarks for anesthesia during drainage of priapism (or during any GU procedure).
To perform a dorsal nerve block, make sure to use lidocaine without epinephrine due to the theoretical risk of ischemia. Clean the area around the pubic symphysis, and then create a wheal of lidocaine. Inject until you hit the pubic symphysis, and then slide anteriorly off the bone to inject more lidocaine. Finally, angle to your needle towards the 10 o’clock and 2 o’clock positions to provide more anesthetic.
A video of a Dorsal Nerve Block is provided here.
You can use ultrasound to aid in your dorsal nerve block. Using the linear probe, you can locate the corpora cavernosa and use Doppler to confirm your needle isn’t injecting into a vessel. You will see something like the image below:
Image from Suleman, M: Cross-sectional anatomy of penis showing injection of lidocaine between Buck’s Fascia and corpus cavernosum, bathing dorsal nerve
Once you have performed the dorsal nerve block, it’s time to perform the actual drainage. To drain priapism, you will need a 20-gauge needle, a sterile field, a blood gas syringe, and multiple larger syringes for draining blood. Inject the needle into the 3 o’clock or 9 o’clock positions to avoid injury to the dorsal vessels or urethra. After injecting, you can send a blood gas sample to help in your evaluation of ischemic versus non-ischemic priapism. Once the blood gas is sent, attached the larger syringe and aspirate blood. You can massage the penis to attempt to aspirate more blood, as both cavernosa communicate through the incomplete septum. Different sources include the use of IV tubing connected to your needle, with a three-way stopcock connected to saline. Using saline and the three-way stopcock, you can alternate aspiration with irrigation to attempt to break up sludge.
Image from Reichman’s Emergency Medicine Procedures: a butterfly needle can be injected into the 3 or 9 o’clock positions with IV tubing and a three-way stopcock. You can alternate aspiration with irrigation
After you aspirate blood, you can inject phenylephrine into the corpus cavernosum to help prevent re-accumulation. Most pharmacies will give you a phenylephrine bottle with 10mg/mL concentration. You should dilute this ten-fold: take one mL of phenylephrine and mix into a 9mL saline flush. Thus, your new concentration will be 1mg/mL, or 1000mcg/mL. After you have completed drainage, you can inject 0.5cc of your phenylephrine mixture into the corpus cavernosa using the same needle you used for drainage (limit to 3 injections).
A video of the drainage procedure is linked here (start at about 4 minutes).
COMPLICATIONS
When using phenylephrine, make sure to place patients on a cardiac monitor. Phenylephrine has a theoretical risk of arrhythmia, so should be used with caution in patients with major cardiac risk factors, cocaine use, MAOIs, and certain other medications (check interactions).
CONSULTS
All patients with priapism should be scheduled for urgent urology follow-up. For patients with recurrent episodes, or where multiple attempts at drainage have proven unsuccessful, you can consider an emergent urology consult.
REFERENCES
- 1. Go S. Priapism Management. Reichman’s Emergency Medicine Procedures. 2019.
- 2. Hootman J and Alvarez A. Trick of the Trade: Angiocatheter for Manual Aspiration of Priapism. ALiEM. 2020. Online.
https://www.aliem.com/trick-of-trade-angiocatheter-manual-aspiration-priapism/ - 3. Rosa T. Emergent Treatment of Ischemic Priapism to Avoid Sexual Dysfunction. US Pharm. 2019;44(8):HS-11-HS-16. Online. https://www.uspharmacist.com/article/emergent-treatment-of-ischemic-priapism-to-avoid-sexual-dysfunction
- 4. Suleman, M. Developing New Techniques: Ultrasound-Guided Penile Nerve Block for Circumcision: A Modified in-Plane Technique. Society for Pediatric Pain Medicine. 2015. Online. https://www.pedspainmedicine.org/wp-content/uploads/newsletters/2015/fall/newtechs.html
- 5. Ting, H.Y.Z., et al. Penile Blocks. Pediatric Atlas of Ultrasound- and Nerve-Stimulation Guided Regional Anesthesia. 2016. Online. https://link.springer.com/chapter/10.1007/978-0-387-79964-3_32#citeas
David Warshaw
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